I grabbed my trusty Field Guide to Germs and, although rabies may have eventually been eliminated in Great Britain, there is a cartoon published in 1826 showing a rabid dog causing panic in the streets of London! Apparently Shakespeare also mentions it, so it's been around in that area for some time. I had to laugh at the advertisement for a rabies remedy "which I hever heard to fail except once." Since rabies was such a horrific and often fatal disease, I think I'll take this testimonial with a grain of salt. The Field Guide also mentions the first(?) successful innoculations against rabies, performed by Louis Pasteur (1822-1895).
I was trying to think of what medicinals (other than the ever-successful gruel) that JA's characters relied upon. Are any mentioned in the novels?